1. Field of the Invention
The present invention relates to a head-protecting air bag device in which gas is ejected from an inflator when a predetermined high load acts on a side portion of a vehicle body, so as to allow an air bag body accommodated along a pillar portion and a roof side rail portion to expand similarly to a curtain.
2. Description of the Related Art
There has already been proposed a head-protecting air bag device in which, in order to improve the ability to protect the head of a vehicle occupant seated in a front seat when a predetermined high load acts on a side portion of a vehicle body, an air bag body accommodated in a folded state over a region from a front pillar portion to a roof side rail portion is caused to expand along a side window glass similarly to a curtain. This type of head-protecting air bag device is disclosed in International Publication No. WO 96/26087 and will be described hereinafter.
As shown in FIG. 11, a head-protecting air bag device 100 is structured to include, as main components, an elongated duct 106 disposed to extend from a front pillar portion 102 to a roof side rail portion 104, an air bag body 112 accommodated in the duct 106 in a folded manner and fixed to the side of a vehicle body at a front-end fixed point 108 and at a rear-end fixed point 110, an inflator 116, which is connected via a hose 114 to the rear end of the duct 106 and when a predetermined high load acts on the side portion of the vehicle body, which the inflator ejects gas, and a band-shaped strap 118 of which one end is fixed to the side of the vehicle body and the other end is fixed to the rear end of the air bag body 112. The air bag device 112 is provided in such a manner that a plurality of cells 120, which are each formed substantially into a cylinder and are disposed with longitudinal direction thereof coinciding with the substantially vertical direction of the vehicle, are connected together.
According to the above-described structure, when a predetermined high load acts on the side portion of the vehicle body, gas is ejected from the inflator 116. For this reason, ejected gas is allowed to flow into each cell 120 of the folded air bag body 112 via the hose 114 and the duct 106. As a result, each cell 120 expands substantially into a cylinder with the longitudinal direction thereof coinciding with the substantially vertical direction of the vehicle, and the air bag body 112 is thereby inflated along a window glass 122 similarly to a curtain. Further, the rear end of the air bag body 112 is connected via the strap 118 to the side of the vehicle body, and therefore, the rear-end side of the air bag body 112 is reliably disposed at an inner side of the upper portion of a center pillar portion 124.
In such a head-protecting air bag device, in order that an upper end portion of the air bag body is fixed to the pillar and to the roof side rail at a plurality of positions, it is preferable to provide, from the viewpoint of assembling efficiency, a structure in which a plurality of tongue-shaped mounting portions are formed projecting in the upper end portion of the air bag body at predetermined intervals, and bolts are inserted into mounting holes respectively formed in the mounting portions so as to fasten the air bag body to a vehicle body.
However, as described above, in the above structure in which the tongue-shaped mounting portions are formed projecting in the upper end portion of the air bag body, and the bolts are inserted into the mounting holes respectively formed in the mounting portions so as to fasten the air bag body to the vehicle body, when the mounting portions are fastened to the vehicle body, each mounting portion may rotate in a direction in which the bolt is fastened and assembling efficiency is thereby deteriorated. Further, when the mounting portion rotates to apply tension to a portion between the rotated mounting portion and an adjacent mounting portion in the air bag body, there arises a drawback in that large tension acts on the portion between the adjacent mounting portions due to expansion force of the air bag body during expansion of the air bag body.